Partial file sharing, don't forget about that. That means you are uploading what you are downloading.

There are programs, Micro$oft & Adobe that download updates, etc. behind the scenes. I stopped allowing M$ access to the net since I use a mac computer.

In post #8 above Suggests you are uploading what you are downloading. Most ISP's count bandwidth as a combination of both bandwidth used for uploading & downloading.

Another alternative of increased bandwidth use is if you are operating as an Ultrapeer, however it should not add that much bandwidth. The option can be disabled under Advanced settings -> Performance.

BTW that was rather amazing about someone else using your bandwidth. So sneaky.